mtl/ofi: Update structs for FI_HMEM support

Update MTL/OFI structs to store needed data.

Signed-off-by: William Zhang <wilzhang@amazon.com>
Co-authored-by: William Zhang <wilzhang@amazon.com>
Co-authored-by: Palmer Stolly <pstolly@amazon.com>

Author: wckzhang

ompi/mca/mtl/ofi/mtl_ofi_request.h

@@ -87,6 +87,10 @@ struct ompi_mtl_ofi_request_t {
 
     /** Pointer to Mrecv request to complete */
     struct mca_mtl_request_t *mrecv_req;
+
+    /** Stores reference to memory region from registration */
+    /*  Set to NULL if memory not registered or if non CUDA buffer */
+    struct fid_mr *mr;
 };
 typedef struct ompi_mtl_ofi_request_t ompi_mtl_ofi_request_t;